1. Field of the Invention
The present invention relates to an integrated circuit, an image processing apparatus, and an image forming apparatus.
2. Description of the Related Art
Electrophotography image forming apparatuses, such as laser printers, digital copiers, and facsimile machines, form electrostatic latent images by scanning charged photoconductors with laser beams emitted from light sources, such as laser diodes (LDs). Specifically, an image forming apparatus scans a charged scanning surface of a photoconductor rotating in the sub-scanning direction with a laser beam shaped by an optical system, such as a collimator lens, while deflecting the laser beam by a polygon mirror in the main-scanning direction, and forms an electrostatic latent image on the scanning surface of the photoconductor. The image forming apparatus forms a toner image by visualizing (developing) the electrostatic latent image formed on the scanning surface of the photoconductor with toner, transfers the toner image to a recording medium such as a printing sheet, and fixes the toner image to the recording medium, to thereby form a certain image.
As described above, in the image forming apparatuses, it is common to perform a process of forming an electrostatic latent image by applying beams to positions corresponding to portions where toner is to be attached on the scanning surface of the photoconductor, and thereafter developing the electrostatic latent image. However, the volume (amount) of the toner to be attached varies depending on the beam diameter of a beam that has reached the scanning surface or depending on other developing conditions. To form an appropriate image, a certain amount of toner is needed. However, if a uniform developing condition is applied, excess toner may be consumed in some cases.
As an image forming apparatus that suppresses toner consumption, there has been proposed an apparatus that extracts an edge portion of an image and sets the densities of pixels of the edge portion and the densities of pixels of portions other than the edge portion to different values (Japanese Laid-open Patent Publication No. 2002-86805). For example, the image forming apparatus described in Japanese Laid-open Patent Publication No. 2002-86805 sets the densities of the pixels of the edge portion to be smaller than the densities of the pixels of the portions other than the edge portion, thereby suppressing the toner consumption and clearly distinguishing the edge portion, that is, a contour, of the image.
Similarly, as an image forming apparatus that suppresses toner consumption, there has been proposed an apparatus that forms a contour image by extracting an edge portion of an image and setting the densities of pixels of portions other than the edge portion to zero or to be smaller than the densities of pixels of the edge portion (Japanese Patent No. 2773081).
In the image forming apparatus, desired print conditions may vary according to users, and it is required to exclusively perform print operation under each print condition. For example, it may be possible to exclusively switch between a print function, in which the densities of pixels of an edge portion of an image is reduced relative to the densities of pixels of a non-edge portion as described in Japanese Laid-open Patent Publication No. 2002-86805, and a print function, in which a contour image is extracted from an original image as described in Japanese Patent No. 2773081. However, if hardware is used to implement image processing for reducing the densities of the pixels of the edge portion of the image relative to the densities of the pixels of the non-edge portion and image processing for extracting the contour image from an original image, it is necessary to provide a separate hardware circuit for each image processing; therefore, the scale of the hardware increases.
The present invention has been conceived in view of the above circumstances, and there is a need for an integrated circuit, an image processing apparatus, and an image forming apparatus that suppress an increase in the scale of hardware for image processing.